lol I actually disagree a little here. Sugar does way more than just sweeten in baking, it affects texture and browning so cutting it too much can mess with the final product. Old recipes like that one probably worked well for a reason, not just because someone copied a cheap filler.
Sugar is cheap filler in a lot of old recipes. Your aunt probably just copied it from someone else who did the same thing. Not everything written down is worth keeping.
Look at my grandma's handwritten pie crust recipe. It calls for a whole cup of sugar and it's the flakiest crust you'll ever eat. Calling that a cheap filler is just wrong.